Written in London surrounded by the large displays at an exhibition and dispatched to silicon.com via a free wi-fi service at 10Mbps.

The number of computers on this planet overtook the number of people long ago, and it looks as though screens will soon do the same.

As a child I remember there being only three screens in my home town, and they were all in cinemas. Then TV sets started to appear and quickly became dominant with more or less one in every home. The digital calculator and wristwatch followed, with the games machines, PCs, mobiles and GPS arriving over the next 20 to 30 years.

Mobile devices now dominate and have overtaken the TV and PC, and look set to overtake the number of humans on the planet. The cumulative number of screens - TVs, PCs, laptops, tablets, games, mobiles and GPS - are far more prevalent than people.

Importance of rare earthsMost screens use rare earths as a vital element in their structure. Worse, these rare earths are also essential for the semiconductors populating all our devices, plus batteries, hybrid vehicles, wind turbines, and low-energy light bulbs.

They may also have an important role in future room-temperature superconductors and nano-tech, as they are already embodied in our industrial phosphors, ceramics and magnets.

So today the world's electronic industry faces a growing shortage and all kinds of dire predictions of the doomsday variety are abroad. Personally I feel rather more sanguine and see some alternatives for industry.

For example, organics may offer viable options. The rare earth route to development was the easiest for industry at the time, but there have always been alternatives.

So I can see potential for the Seven Screens of Life - cinema, TV, PC, laptop, tablet, mobile and GPS - migrating rapidly to a far more eco-friendly formats that I might feel happy about burying in the garden when they reach the end of their useful life.